Drive mechanism for a medication delivery device and medication delivery device

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent application Ser. No. 14/459,440, filed Aug. 14, 2014, which is a continuation of U.S. patent application Ser. No. 13/133,884, filed Dec. 21, 2011, which is a U.S. National Phase application pursuant to 35 U.S.C. §371 of International Application No. PCT/EP2009/066742 filed Dec. 9, 2009, which is a continuation-in-part of U.S. patent application Ser. No. 12/333,459, filed Dec. 12, 2008, now U.S. Pat. No. 8,840,591, and claims priority to European Patent Application No. 08021628.6, filed Dec. 12, 2008. The entire disclosure content of these applications is herewith incorporated by reference into the present application.

FIELD OF THE INVENTION

The present invention relates to a drive mechanism fir a medication delivery device and a medication delivery device incorporating such a drive mechanism.

BACKGROUND

In a medication delivery device, a piston within a cartridge that contains medication may be displaced with respect to the cartridge in the distal direction by a piston rod which moves in the distal direction with respect to the cartridge. Thereby, a dose of medication can be expelled from the cartridge. A medication delivery device is described in US 2007/0123829 A1, for example.

It is often desirable that the actually delivered dose of medication matches the dose which was previously set for injection by a user or which the device was designed to deliver as close as possible, i.e. dose accuracy should be good.

It is an object to provide for a drive mechanism that facilitates provision of an improved medication delivery device, for example a device with good dose accuracy. Furthermore, an improved medication delivery device should be provided for.

This object may be achieved by a drive mechanism according to the independent claim. Further features, advantages and expediencies are subject matter of the dependent claims.

SUMMARY

According to one aspect, a drive mechanism for a medication delivery device comprises a housing having a proximal end and a distal end, a rotation member which is adapted to be rotated in a first direction with respect to the housing during setting of a dose of a medication and to be rotated in a second direction with respect to the housing during delivery of the dose, the second direction being opposite to the first direction. Furthermore, the drive mechanism comprises a piston rod which is adapted to be displaced in a distal direction with respect to the housing for delivering the dose, a drive member which follows rotational movement of the rotation member in the second direction during delivery of the dose, and a stop member which prevents rotational movement of the drive member with respect to the housing in the first direction during setting of the dose, wherein the rotational movement of the drive member in the second direction is converted into movement of the piston rod in the distal direction with respect to the housing.

Mechanical interaction of stop member and drive member, for example, interlocking, engagement and/or abutment, during rotation of the rotation member in the first direction may prevent rotational movement of the drive member with respect to the housing in the first direction and, in particular, with respect to the stop member during setting of the dose. Thus, rotation of the drive member during dose setting can be avoided. The drive member may be coupled to the piston rod so as to convert its rotational movement in the second direction into distal movement of the piston rod with respect to the housing. The drive member may (also) be coupled to the piston rod so as to convert its rotational movement in the first direction with respect to the housing into proximal movement of the piston rod with respect to the housing. Accordingly, the risk of the piston rod being moved in the proximal direction during dose setting can be reduced by preventing rotational movement of the drive member in the first direction during setting of the dose due to provision of the stop member. Unintentional proximal movement of the piston rod may result in decreased dose accuracy. Consequently, dose accuracy may be improved by preventing (any) rotation of the drive member with respect to the housing during dose setting.

According to a preferred embodiment, the drive member and the rotation member are rotatable around a common rotation axis.

According to another preferred embodiment, the piston rod is displaced in the distal direction with respect to the housing along the rotation axis. The rotation axis may run along the piston rod and, in particular, along a main direction of extent of the piston rod.

According to another preferred embodiment, the piston rod is displaced in the distal direction with respect to the housing transversally with respect to the rotation axis. The rotation axis may, in particular, run transversally, for example perpendicularly, with respect to a displacement axis along which the piston rod is displaced in the distal direction with respect to the housing and, in particular, with respect to the drive member. The displacement axis may run along the piston rod and, in particular, along a main direction of extent of the piston rod.

According to another preferred embodiment, the drive mechanism comprises a dose member. The dose member is preferably movable with respect to the housing during setting and/or delivery of the dose. The dose member may be movable in the proximal direction with respect to the housing for setting the dose. The dose member may be movable in the distal direction with respect to the housing for delivering the set dose. Movement of the dose member with respect to the housing may be converted into rotational movement of the rotation member with respect to the housing. Movement of the dose member for setting the dose may be converted into rotational movement of the rotation member with respect to the housing in the first direction. Movement of the dose member for delivering the set dose may be converted into rotational movement of the rotation member with respect to the housing in the second direction. The dose member may be secured against rotational movement with respect to the housing. The dose member may be splined to the housing, for example. The dose member may be movable with respect to the rotation member. Movement of the dose member with respect to the rotation member may be converted into rotational movement of the rotation member.

According to another preferred embodiment, the dose member and the rotation member are engaged, preferably threadedly engaged and/or permanently engaged. Rotational movement of the rotation member may be achieved by the (threaded) engagement which may convert (linear) movement of the dose member into rotational movement of the rotation member with respect to the housing.

According to another preferred embodiment, the dose member and the rotation member are coupled to one another via or (immediately) by a lever. The lever may be pivotally around the rotation axis during movement of the dose member for setting and/or delivery of the dose. The lever may be pivotally around the rotation axis in the first direction during movement of the dose member for setting of the dose. The lever may be pivotally around the rotation axis in the second direction during movement of the dose member for delivering the dose.

According to another preferred embodiment, the drive member, preferably permanently, abuts and/or engages one of or both of stop member and rotation member during (rotational) movement of the rotation member for setting and delivery of the dose. The drive member may be coupled to stop member and/or rotation member during setting and delivery of the dose.

According to another preferred embodiment, the drive member is arranged between stop member and rotation member.

According to another preferred embodiment, the rotation member and the drive member and/or the stop member and the drive member are held in abutment by a force provided by a resilient member, in particular a spring member, during setting and delivery of the dose, in particular during rotational movement of the rotation member in the first direction and in the second direction. Preferably, the rotation member and the stop member are held in abutment with the drive member by the force provided by the spring member during setting and delivery of the dose.

According to another preferred embodiment, the drive member and the rotation member are coupled, preferably permanently, to one another by a (first) uni-directional friction clutch mechanism. This friction clutch mechanism may be configured to permit relative rotational movement between rotation member and drive member during movement of the rotation member for setting of the dose and to prevent relative rotational movement of rotation member and drive member during movement of the rotation member for delivery of the dose.

According to another preferred embodiment, the drive member and the stop member are coupled, preferably permanently, to one another by a (second) uni-directional friction clutch mechanism. This friction clutch mechanism may be configured to prevent relative rotational movement between stop member and drive member during movement of the rotation member for setting of the dose and to permit relative rotational movement of stop member and drive member during movement of the rotation member for delivery of the dose.

According to another preferred embodiment, the stop member is secured against rotational movement with respect to the housing.

According to another preferred embodiment, the stop member is (linearly) displaceable with respect to the housing, preferably without rotating. The stop member may be displaceable along the rotation axis with respect to the housing. The rotation member may be secured against displacement with respect to the housing. Alternatively, the rotation member is displaceable with respect to the housing. Rotation member and stop member may be displaceable with respect to the housing.

Alternatively, the stop member may be secured against rotation and displacement with respect to the housing. The rotation member may be displaceable with respect to the housing, in this case.

According to another preferred embodiment, the spring member abuts the stop member or is integrated in the stop member.

According to another preferred embodiment, the drive member, the stop member, the rotation member and/or the dose member may be formed as or may comprise a sleeve. A rod, for example the piston rod or an axis rod which defines the rotation axis may extend through one of, more of or all of drive sleeve, stop sleeve, rotation sleeve and dose sleeve.

According to another preferred embodiment, the drive member engages the piston rod.

According to another preferred embodiment, the drive member is splined to the piston rod.

According to another preferred embodiment, the rotational movement of the drive member in the second direction is converted into rotational movement of the piston rod with respect to the housing, in particular rotational movement in the same direction and/or by the same angle, and movement of the piston rod with respect to the housing in the distal direction. The piston rod may be threadedly coupled to the housing, in particular threadedly engaged with the housing, for this purpose.

According to another preferred embodiment, the rotational movement of the drive member is converted into pure linear movement of the piston rod in the distal direction. Accordingly, the piston rod may be moved in the distal direction without rotating with respect to the housing. It is particularly suitable for the drive member to comprise (radial) gear teeth for engaging the piston rod, for this purpose.

Another aspect relates to a medication delivery device that comprises a drive mechanism as described above. The device furthermore comprises a cartridge that comprises a plurality of doses of a medication. A piston may be arranged within the cartridge, the piston being displaceable in the distal direction with respect to the cartridge for delivering a dose of medication from the cartridge. The piston rod may be arranged to drive the piston in the distal direction with respect to the cartridge. The cartridge may be attached, permanently or releasably, to the housing.

Features which are described herein above and below in connection with the drive mechanism may also be applied for the corresponding medication delivery device and vice versa.

Further features, refinements and expediencies become apparent from the following description of the exemplary embodiments in connection with the figures.

BRIEF DESCRIPTION OF THE FIGURES

<figref idref="DRAWINGS">FIG. 1</figref> schematically shows a partly sectional side view of an exemplary embodiment of a medication delivery device.

<figref idref="DRAWINGS">FIG. 2</figref> schematically shows a perspective sectional view of a part of a drive mechanism according to a first embodiment with schematically indicated movements of elements thereof during setting of a dose.

<figref idref="DRAWINGS">FIG. 3</figref> schematically shows a more detailed side view of a part of <figref idref="DRAWINGS">FIG. 2</figref>.

<figref idref="DRAWINGS">FIG. 4</figref> schematically shows a perspective sectional view of a part of the drive mechanism according to the first embodiment with indicated movements of elements thereof during delivery of a dose.

<figref idref="DRAWINGS">FIG. 5</figref> schematically shows a more detailed side view of a part of <figref idref="DRAWINGS">FIG. 4</figref>.

<figref idref="DRAWINGS">FIG. 6</figref> schematically shows a perspective sectional view of a part of a drive mechanism that is configured in accordance with the first embodiment.

<figref idref="DRAWINGS">FIG. 7</figref> schematically shows a perspective view of a part of the drive mechanism of <figref idref="DRAWINGS">FIG. 2</figref> with indicated movements of elements thereof during delivery of a dose.

<figref idref="DRAWINGS">FIG. 8</figref> schematically shows a perspective view of a part of a drive mechanism that is configured in accordance with the first embodiment.

<figref idref="DRAWINGS">FIG. 9</figref> schematically shows a perspective view of a part of a drive mechanism that is configured in accordance with the first embodiment.

<figref idref="DRAWINGS">FIG. 10</figref> schematically shows an oblique sectional view of a drive mechanism according to a second embodiment.

<figref idref="DRAWINGS">FIG. 11</figref> schematically shows an oblique sectional view of a drive mechanism according to a third embodiment.

<figref idref="DRAWINGS">FIG. 12</figref> schematically shows an oblique sectional view of a part of the drive mechanism of <figref idref="DRAWINGS">FIG. 11</figref>.

<figref idref="DRAWINGS">FIG. 13</figref> schematically shows an oblique sectional view of a part of the drive mechanism of <figref idref="DRAWINGS">FIG. 11</figref>.

<figref idref="DRAWINGS">FIG. 14</figref> schematically shows an oblique sectional view of a part of the drive mechanism of <figref idref="DRAWINGS">FIG. 11</figref>.

<figref idref="DRAWINGS">FIG. 15</figref> schematically shows an oblique sectional view of a part of the drive mechanism of <figref idref="DRAWINGS">FIG. 11</figref>.

<figref idref="DRAWINGS">FIG. 16</figref> shows a schematic sectional view of a part of a resettable drive mechanism according to an embodiment in delivery position.

<figref idref="DRAWINGS">FIG. 17</figref> shows the resettable drive mechanism of <figref idref="DRAWINGS">FIG. 16</figref> in reset position.

Like elements, elements of the same kind and identically acting elements are provided with the same reference numerals in the figures.

DETAILED DESCRIPTION

Turning now to <figref idref="DRAWINGS">FIG. 1</figref>, a medication delivery device <b>1</b> comprises a cartridge unit <b>2</b> and a drive unit <b>3</b>. The cartridge unit <b>2</b> comprises a cartridge <b>4</b>. Medication <b>5</b> is retained in the cartridge <b>4</b>. The medication <b>5</b> is preferably liquid medication. The cartridge <b>4</b> preferably comprises a plurality of doses of the medication <b>5</b>. The medication <b>5</b> may comprise insulin, heparin, or growth hormones, for example. The cartridge <b>4</b> has an outlet <b>6</b> at its distal end. Medication <b>5</b> can be dispensed from the cartridge through outlet <b>6</b>. The device <b>1</b> may be a pen-type device, in particular a pen-type injector. The device <b>1</b> may be a disposable or a reusable device. The device <b>1</b> may be a device configured to dispense fixed doses of the medication or variable, preferably user-settable, doses. The device <b>1</b> may be a needle-based or a needle free device. The device <b>1</b> may be an injection device.

The term “distal end” of the medication delivery device <b>1</b> or a component thereof may refer to that end of the device or the component which is closest to the dispensing end of the device <b>1</b>. The term “proximal end” of the medication delivery device <b>1</b> or a component thereof may refer to that end of the device or the component which is furthest away from the dispensing end of the device. In <figref idref="DRAWINGS">FIG. 1</figref>, the distal end of the device <b>1</b> was assigned reference numeral <b>7</b> and the proximal end of the device was assigned reference numeral <b>8</b>.

The outlet <b>6</b> may be covered by a membrane <b>9</b>, which protects medication <b>5</b> against external influences during storage of the cartridge. For medication delivery, membrane <b>9</b> may be opened, e.g. pierced. For example, membrane <b>9</b> may be pierced by a needle unit (not explicitly shown). The needle unit may be (releasably) attached to the distal end of the cartridge unit <b>2</b>. The needle unit may provide for fluid communication from the inside of the cartridge <b>4</b> to the outside of the cartridge through outlet <b>6</b>.

A piston <b>10</b> is retained within the cartridge <b>4</b>. The piston <b>10</b> is movable with respect to the cartridge. The piston <b>10</b> may seal the medication <b>5</b> within the cartridge. The piston <b>10</b> expediently seals the interior of the cartridge <b>4</b> proximally. Movement of the piston <b>10</b> with respect to the cartridge <b>4</b> in the distal direction causes medication <b>5</b> to be dispensed from the cartridge through outlet <b>6</b> during operation of the device.

The cartridge unit <b>2</b> furthermore comprises a cartridge retaining member <b>11</b>. The cartridge <b>4</b> is retained within the cartridge retaining member <b>11</b>. The cartridge retaining member <b>11</b> may stabilize the cartridge <b>4</b> mechanically. Additionally or alternatively, the cartridge retaining member <b>11</b> may be provided with a fixing member (not explicitly shown) for attaching the cartridge unit <b>2</b> to the drive unit <b>3</b>.

The cartridge unit <b>2</b> and the drive unit <b>3</b> are secured to one another, preferably releasably secured. A cartridge unit <b>2</b> which is releasably secured to the drive unit may be detached from the drive unit <b>3</b>, for example in order to allow for providing for a new cartridge <b>4</b>, if all of the doses of medication which once were in the cartridge formerly attached to the drive unit <b>3</b> have already been dispensed. The cartridge retaining member <b>11</b> may be releasably secured to the drive unit <b>3</b> via a thread, for example.

Alternatively, the cartridge retaining member <b>1</b>I may be dispensed with. It is particularly expedient, in this case, to apply a robust cartridge <b>4</b> and to attach the cartridge directly to the drive unit <b>3</b>.

The drive unit <b>3</b> is configured for transferring force, preferably user-exerted force, particularly preferably manually exerted force, to the piston <b>10</b> for displacing the piston <b>10</b> with respect to the cartridge <b>4</b> in the distal direction. A dose of medication may be dispensed from the cartridge in this way. The size of the delivered dose may be determined by the distance by which the piston <b>10</b> is displaced with respect to the cartridge <b>4</b> in the distal direction.

The drive unit <b>3</b> comprises a drive mechanism. The drive mechanism comprises a piston rod <b>12</b>. The piston rod <b>12</b> may be configured for transferring force to the piston <b>10</b>, thereby displacing the piston in the distal direction with respect to the cartridge <b>4</b>. A distal end face of the piston rod <b>12</b> may be arranged to abut a proximal end face of the piston <b>10</b>. A bearing member (not explicitly shown) may be arranged to advance the piston <b>10</b>, preferably to abut the proximal end face of the piston <b>10</b>. The bearing member may be arranged between piston <b>10</b> and piston rod <b>12</b>. The bearing member may be fixed to the piston rod <b>12</b> or a separate member. If the piston rod <b>12</b> is configured to be rotated during operation of the device, for example during dose delivery, it is particularly expedient to provide for a bearing member. The bearing member may be displaced together with the (rotating) piston rod with respect to the housing. The piston rod may be rotatable with respect to the bearing member. In this way, the risk that the rotating piston rod drills into the piston and thereby damages the piston is reduced. Accordingly, while the piston rotates and is displaced with respect to the housing, the bearing member is preferably only displaced, i.e. does not rotate. The piston rod may be bounded by the bearing member.

The drive unit <b>3</b> comprises a housing <b>13</b> which may be part of the drive mechanism. The piston rod <b>12</b> may be retained in the housing. A proximal end side <b>14</b> of the cartridge unit <b>2</b> may be secured to the drive unit <b>3</b> at a distal end side <b>15</b> of the housing <b>13</b>, for example via a threaded connection. Housing <b>13</b>, cartridge <b>4</b> and/or cartridge retaining member <b>11</b> may have a tubular shape.

The term “housing” shall preferably mean any exterior housing (“main housing”, “body”, “shell”) or interior housing (“insert”, “inner body”) which may have a unidirectional axial coupling to prevent proximal movement of specific components. The housing may be designed to enable the safe, correct, and comfortable handling of the medication delivery device or any of its mechanism. Usually, it is designed to house, fix, protect, guide, and/or engage with any of the inner components of the medication delivery device (e.g., the drive mechanism, cartridge, piston, piston rod), preferably by limiting the exposure to contaminants, such as liquid, dust, dirt etc. In general, the housing may be unitary or a multipart component of tubular or non-tabular shape.

The term “piston rod” shall preferably mean a component adapted to operate through/within the housing, which may be designed to transfer axial movement through/within the medication delivery device, preferably from the drive member to the piston, for example for the purpose of discharging/dispensing an injectable product. Said piston rod may be flexible or not. It may be a simple rod, a lead-screw, a rack and pinion system, a worm gear system, or the like. “piston rod” shall further mean a component having a circular or non-circular cross-section. It may be made of any suitable material known by a person skilled in the art and may be of unitary or multipart construction.

The drive unit <b>3</b> comprises a dose part <b>16</b>. The dose part <b>16</b> is movable with respect to the housing <b>13</b>. The dose part <b>16</b> may be movable in the proximal direction with respect to the housing for setting of a dose of the medication <b>5</b> which is to be delivered and in the distal direction with respect to the housing for delivery of the set dose. The dose part <b>16</b> is preferably connected to the housing <b>13</b>. The dose part <b>16</b> may be secured against rotational movement with respect to the housing. The dose part <b>16</b> may be moved (displaced) between a proximal end position and a distal end position with respect to the housing <b>13</b> (not explicitly shown). The distance by which the dose part is displaced with respect to the housing during setting of the dose may determine a size of the dose. The proximal end position and the distal end position may be determined by a respective stop feature which may limit the proximal or distal travel of the dose member with respect to the housing. The device <b>1</b> may be a variable dose device, i.e. a device configured for delivering doses of medication of different, preferably user-settable, sizes. Alternatively, the device may be a fixed dose device.

The device <b>1</b> may be a manually, in particular non-electrically, driven device. The (user-applied) force which causes the dose part <b>16</b> to be moved with respect to the housing <b>13</b> in the distal direction may be transferred to the piston rod <b>12</b> by the drive mechanism. For this purpose, other elements of the drive mechanism may be provided which are not explicitly shown in <figref idref="DRAWINGS">FIG. 1</figref>. The drive mechanism is preferably configured to not move the piston rod <b>12</b> with respect to the housing <b>13</b> when the dose part is moved in the proximal direction with respect to the housing for setting of the dose.

Embodiments of a drive mechanism which are suitable to be provided in the medication delivery device <b>1</b> as it was described above are described in more detail below.

A first embodiment of a drive mechanism which is suitable for being implemented in the medication delivery device <b>1</b> as described above is described in connection with <figref idref="DRAWINGS">FIGS. 2 to 9</figref>.

The drive mechanism comprises a housing part <b>17</b>. The housing part <b>17</b> has a proximal end <b>18</b> and a distal end <b>19</b>. The housing part <b>17</b> may be (outer) housing <b>13</b> of <figref idref="DRAWINGS">FIG. 1</figref>, a part thereof or an insert within housing <b>13</b>, which insert is preferably secured against rotational and axial movement with respect to housing <b>13</b>. The housing part <b>17</b> may be an insert sleeve, for example. The insert sleeve may be snap-fitted or glued to housing <b>13</b>, for example. The housing part <b>17</b> may have a tubular shape. Housing part <b>17</b> may comprise outer fixing elements <b>64</b>, for example snap-fit elements, for fixing housing part <b>17</b> to housing <b>13</b> (cf. <figref idref="DRAWINGS">FIG. 8</figref>).

The piston rod <b>12</b> is retained in the housing <b>113</b>, preferably within housing part <b>17</b>. The piston rod <b>12</b> is driven in the distal direction with respect to the housing part <b>17</b> during dose delivery.

The drive mechanism furthermore comprises a drive member <b>20</b>. Drive member <b>20</b> is retained within the housing part <b>17</b>. Drive member <b>20</b> is configured to transfer force, preferably torque, to the piston rod <b>12</b>. The transferred force may cause the piston rod <b>12</b> to be displaced in the distal direction with respect to the housing part <b>17</b> for dose delivery.

Drive member <b>20</b> is rotatable with respect to housing part <b>17</b>. The drive member <b>20</b> may engage the piston rod <b>12</b>. Rotational movement of the drive member, fir example rotational movement in a second direction may be converted into distal movement of the piston rod <b>12</b> with respect to the housing part <b>17</b>. This is explained in more detail below.

The drive mechanism furthermore comprises a rotation member <b>21</b>. The rotation member <b>21</b> is rotatable with respect to the housing part <b>17</b> in a first direction, in particular for setting of a dose of the medication, and in a second direction, in particular for delivering the set dose. The second direction is opposite to the first direction. The first direction may be counter-clockwise and the second direction may be clockwise as seen from the proximal end of the device, for example.

Drive member, rotation member and/or piston rod are preferably configured to be rotatable about a (common) rotation axis. The rotation axis may extend through drive member, rotation member and/or piston rod. The rotation axis may be the main longitudinal axis of the piston rod. The rotation axis may run between the proximal end and the distal end of the housing part <b>17</b>.

The rotation member <b>21</b> is coupled to the drive member <b>20</b> by an uni-directional clutch mechanism, in particular a friction clutch mechanism. This clutch mechanism permits rotational movement of the rotation member <b>21</b> with respect to the drive member <b>20</b> when the rotation member rotates in the first direction with respect to the housing part <b>17</b>. The clutch mechanism prevents rotational movement of the rotation member <b>21</b> with respect to the drive member <b>20</b>, when the rotation member rotates in the second direction with respect to the housing part <b>17</b>. The drive member <b>20</b> may thus follow rotational movement of the rotation member <b>21</b> in the second direction with respect to the housing part <b>17</b>.

The drive member <b>20</b> is arranged to abut and/or engage the rotation member and, in particular, engages rotation member <b>21</b>. The drive member <b>20</b> comprises a toothing <b>22</b> at one end, e.g. its proximal end. The rotation member comprises a toothing <b>23</b> at one end which end faces the drive member <b>20</b>, e.g. its distal end. Toothing <b>22</b> comprises a plurality of teeth <b>24</b>. Toothing <b>23</b> comprises a plurality of teeth <b>25</b>. Teeth <b>24</b> and/or <b>25</b> may extend along the rotation axis. Toothings <b>22</b> and <b>23</b> may be configured to mate with one another.

A respective tooth of teeth <b>24</b> and/or teeth <b>25</b> may be ramp-shaped, in particular along the azimuthal (angular) direction as seen from the rotation axis. The ramp of the respective tooth is limited (in the angular direction) by a steep end face of that tooth, i.e. a face of the tooth that runs parallel to the rotation axis or includes a smaller angle with the rotation axis when projected on this axis than the ramp when projected on this axis. The steep end face is followed by the ramp of the next tooth.

The teeth <b>24</b> may be disposed along the perimeter of that end of the drive member <b>20</b> which faces the rotation member <b>21</b>. The teeth <b>25</b> may be disposed along the perimeter of the rotation member <b>21</b> at that end which faces the drive member <b>20</b>.

When the steep end faces of two teeth abut and the rotation member is rotated further on in the second direction, the steep sides stay in abutment and drive member <b>20</b> follows the rotation of rotation member <b>21</b>. When the rotation member rotates in the first direction, the ramp of the teeth—which ramps, in particular, run obliquely with respect to the rotation axis—slide along each other and, in consequence, the rotation member <b>21</b> may rotate with respect to the drive member <b>20</b>.

The drive mechanism furthermore comprises a stop member <b>26</b>. The drive member may be arranged between the stop member <b>26</b> and the rotation member <b>21</b>. The stop member <b>26</b> is configured for preventing rotational movement of the drive member <b>20</b> in the first direction with respect to the housing part <b>17</b> during setting of a dose, i.e. when the rotation member rotates in the first direction. Thus, the rotation member <b>21</b> may rotate in the first direction with respect to the housing part <b>17</b>, whereas the drive member <b>20</b> and the stop member <b>21</b> don't rotate.

The stop member <b>26</b> is coupled to the drive member <b>20</b> by another uni-directional clutch mechanism, in particular a friction clutch mechanism. This clutch mechanism prevents rotational movement of the drive member <b>20</b> with respect to the stop member <b>20</b> when the rotation member rotates in the first direction with respect to the housing part <b>17</b>. The clutch mechanism permits rotational movement of the drive member <b>20</b> with respect to the stop member <b>26</b>, when the rotation member rotates in the second direction with respect to the housing part <b>17</b>.

Thus, the rotation member <b>21</b> may rotate with respect to the drive member <b>20</b> and the stop member <b>26</b> in the first direction during setting of the dose, with rotation of the drive member being prevented by its interaction with the stop member, and rotation member as well as drive member may rotate with respect to the stop member in the second direction during delivery of the dose.

The stop member may be arranged to abut and/or engage the drive member during setting of the dose and, preferably, during delivery of the dose. The stop member <b>26</b> has a toothing <b>27</b> at one end which faces the drive member, e.g. its proximal end. The teeth may be ramp-shaped with a steep side and a less steep ramp. The teeth may be disposed azimuthally along the perimeter of the stop member.

Drive member <b>20</b> has a toothing <b>28</b> at one end which faces the stop member, e.g. its distal end. Toothings <b>22</b> and <b>28</b> of the drive member <b>20</b> are oppositely disposed. Toothing <b>28</b> may be configured in accordance with toothing <b>21</b> of the rotation member. Toothing <b>22</b> may be configured in accordance with toothing <b>27</b> of the stop member. Toothings <b>27</b> and <b>28</b>, in particular the steep sides of the teeth, do cooperate, e.g. abut, for preventing rotation of the drive member <b>20</b> with respect to the housing part <b>17</b> and, in particular, with respect to the stop member <b>26</b> in the first direction.

Stop member <b>26</b> is preferably secured against rotational movement with respect to the housing part <b>17</b>. Stop member <b>26</b> may be fixed to the housing or integrated into the housing. Stop member <b>26</b> may be fixed against displacement with respect to the housing part <b>17</b> or displacement with respect to the housing part <b>17</b> may be allowed.

As it is illustrated in the present embodiment, stop member <b>26</b> is displaceable with respect to the housing but non-rotatable with respect to the housing part <b>17</b>. For that purpose, one or a plurality of, preferably oppositely disposed, guide features, for example guide lugs <b>29</b>, are provided in the stop member <b>26</b>. The respective guide feature <b>29</b> engages a corresponding guide slot <b>30</b> which may be provided in the housing, e.g. in housing part <b>17</b>. This can be seen in <figref idref="DRAWINGS">FIGS. 2 to 5</figref>. A guide feature <b>29</b> cooperates with a guide slot <b>30</b> to prevent rotational movement of the stop member with respect to the housing part <b>17</b>, with axial movement of the stop member <b>26</b> with respect to the housing being allowed. The axial movement of the stop member <b>26</b> may compensate for play between components of the drive mechanism during operation.

From the group comprising drive member <b>20</b>, stop member <b>26</b> and rotation member <b>21</b> one or more members, preferably two members or three members, may be axially displaceable with respect to the housing part <b>17</b> and, preferably, with respect to the piston rod <b>12</b>. Therein, the drive member and another one of the recited members may be axially displaceable with respect to the housing. The remaining member may be secured against axial displacement or may also be axially displaceable during operation of the drive mechanism for medication delivery. Accordingly, if the drive member and the stop member are axially displaceable, the rotation member may be axially secured or axially displaceable and so on. Play between the components caused by relative (axial) movement of components of the clutch mechanism with respect to the housing can be compensated for in this way. The distance by which the respective components may be axially displaced with respect to the housing may correspond to the (maximum) depth of a tooth of the respective toothing <b>22</b> or <b>28</b> of the drive member. Alternatively, the distance may be greater than the (maximum) depth of a tooth of the respective toothing.

Furthermore, the drive mechanism comprises a resilient member <b>31</b>, preferably a spring member. The resilient member <b>31</b> may be biased during medication delivery operation of the drive mechanism. The resilient member may provide for a force that tends to keep the drive member <b>20</b> in engagement with the stop member <b>26</b> and/or the rotation member <b>21</b>. The force may be exerted along the rotation axis. In the situation shown in <figref idref="DRAWINGS">FIGS. 2 to 5</figref>, this force may be exerted in the proximal direction. The resilient member <b>31</b> may be a helical (coil) spring. The resilient member <b>31</b> may be a compression spring.

The resilient member <b>31</b> may keep the drive member <b>20</b> and the stop member <b>26</b> in (permanent) mechanical contact, e.g. in abutment, with each other during setting and delivery of a dose of the medication. Alternatively or additionally, the resilient member <b>31</b> may keep the drive member <b>20</b> and the rotation member <b>26</b> in (permanent) mechanical contact, preferably abutment, with each other during setting and delivery of a dose of the medication.

The resilient member <b>31</b> may be integrated within stop member <b>26</b> or a separate component. The resilient member <b>31</b> may be arranged on the distal end side of the stop member <b>26</b>.

The drive mechanism furthermore comprises a support member <b>32</b>. Support member <b>32</b> is expediently fixed against axial and rotational movement with respect to the housing part <b>17</b> or integrated into housing part <b>17</b>. Support member <b>32</b> is arranged on that side of the drive member <b>20</b> which is remote from the stop member <b>26</b>. Support member <b>32</b> may be a protrusion, for example a ring-like protrusion. Rotation member <b>21</b> may extend through an opening in support member <b>32</b>. The support member <b>32</b> may provide for a counter force to the force which is exerted by the resilient member <b>31</b>. Permanent abutment of the rotation member with the drive member and of the drive member with the stop member during setting and delivery of medication is facilitated in this way.

The rotation member <b>21</b> has an (radially) outwardly protruding member <b>33</b>, for example a flange portion. The protruding member <b>33</b> is expediently provided for abutting support member <b>32</b>, in particular the distal end side of support member <b>32</b>.

Another support <b>48</b> (cf. <figref idref="DRAWINGS">FIG. 6</figref>) may be provided for providing a counterforce to the force exerted by the resilient member <b>31</b>. Support <b>48</b> is arranged on that side of the drive member <b>20</b> which is remote from the rotation member <b>21</b>. Support <b>48</b> is arranged on that side of the stop member <b>26</b> which is remote from the support member <b>32</b>. The support <b>48</b> may be arranged to abut the resilient member <b>31</b>. The support <b>48</b> may be secured against axial and rotational movement with respect to the housing part <b>17</b>, with respect to the housing <b>13</b> or integrated into the housing <b>13</b>, for example into (additional) housing part <b>40</b> (cf. <figref idref="DRAWINGS">FIG. 6</figref>).

The drive mechanism furthermore comprises a dose member <b>34</b>. Dose member <b>34</b> may be dose part <b>16</b> or may be a part of the dose part <b>16</b> of <figref idref="DRAWINGS">FIG. 1</figref>. Dose member <b>34</b> is movable with respect to the housing in the proximal direction for setting of a dose and for delivery of the dose. For example, the dose member <b>34</b> may be moved in the proximal direction with respect to the housing part <b>17</b> during dose setting and in the distal direction with respect to the housing part <b>17</b> during dose delivery. The dose member <b>34</b> may engage the housing part <b>17</b> or, alternatively, another part of housing <b>13</b> (not explicitly shown). Dose member <b>34</b> is preferably secured against rotational movement with respect to the housing part <b>17</b>. The dose member <b>34</b> may comprise a guide feature <b>35</b>, for example a guide lug or a guide slot, that engages another guide feature, for example a guide slot or a guide lug, respectively, that is provided in the housing part <b>17</b> or the housing <b>13</b>.

Dose member <b>34</b> may be moved in the proximal direction and in the distal direction with respect to rotation member <b>21</b>. Dose member <b>34</b> is arranged to be couplable and is preferably (permanently) coupled to rotation member <b>21</b> such that movement of the dose member, e.g. in the proximal direction with respect to the housing part <b>17</b>, for setting a dose of the medication is converted into rotational movement of the rotation member in the first direction and movement of the dose member, e.g. in the proximal direction with respect to the housing part <b>17</b>, for delivering the dose is converted into rotational movement of the rotation member <b>21</b> in the second direction opposite to the first direction.

The rotation member <b>21</b> may be provided with an (outer) thread <b>36</b>. Thread <b>36</b> may be engaged with one of or a plurality of engagement members <b>42</b> of dose member <b>34</b>. The respective engagement member may be arranged on the inside of the dose member. The respective engagement member may be a thread or a part of a thread, for example. Thus, dose member <b>34</b> and rotation member <b>21</b> may be threadedly coupled, in particularly threadedly engaged. The rotation member <b>21</b> may be arranged inside the dose member <b>21</b>.

The rotation member <b>21</b>, the drive member <b>20</b>, the stop member <b>26</b> and/or the dose member <b>34</b> may be or may comprise a respective sleeve. The piston rod <b>12</b> may be arranged to be driven and, in particular, may be driven through one of, more of or all of those sleeves. The piston rod <b>12</b> may run through one of more of or all of those sleeves.

The drive member <b>20</b> and the piston rod <b>12</b> are configured fir rotational movement of the drive member <b>20</b> with respect to the housing being converted into rotational movement of the piston rod with respect to the housing. The drive member <b>20</b> may engage the piston rod <b>12</b>. The piston rod <b>12</b> is displaceable with respect to the drive member <b>20</b> along a displacement axis. Presently, the displacement axis runs along the rotation axis. The drive member <b>20</b> may be splined to the piston rod <b>12</b>, for example.

The piston rod <b>12</b> is threadedly coupled to the housing <b>13</b>. The piston rod <b>12</b> may be provided with an outer thread <b>49</b>, for example. The piston rod <b>12</b> may extend through and be engaged with a (part) thread in opening <b>39</b> which is provided in housing part <b>40</b>, for example in support <b>48</b> (cf. <figref idref="DRAWINGS">FIG. 6</figref>). Housing part <b>40</b> may be formed integrally with housing part <b>17</b>, may be a housing part fixed thereto or may be a housing part secured separately from housing part <b>17</b> to housing <b>13</b>.

The piston rod <b>12</b> comprises an engagement track <b>37</b>, preferably two oppositely disposed engagement tracks, on the outside. The (respective) engagement track <b>37</b> may interrupt thread <b>49</b>. The (respective) engagement track <b>37</b> preferably extends along the axia along which the piston rod is displaceable with respect to the housing and, in particular, with respect to the drive member.

Rotational movement of the drive member <b>20</b> with respect to the housing may thus be converted into rotational movement of the piston rod <b>12</b> with respect to the housing and the rotational movement of the piston rod <b>12</b> is, on account of the threaded engagement of the piston rod and the housing (part), converted into movement of the piston rod with respect to the housing in the distal direction.

The dose part <b>16</b> (cf. <figref idref="DRAWINGS">FIG. 1</figref>) may comprise a dose knob <b>41</b> (cf. <figref idref="DRAWINGS">FIG. 8</figref>). Dose knob <b>41</b> may be configured to be gripped by a user. Dose knob <b>41</b> may be arranged and connected to the dose member <b>34</b> at the proximal end. Dose knob and dose member may be unitary.

In the following, operation of the present drive mechanism for delivering medication from the cartridge <b>4</b> of <figref idref="DRAWINGS">FIG. 1</figref> is described.

To set a dose, a user may manually move dose member <b>34</b> in the proximal direction (arrow <b>43</b>) with respect to the housing part <b>17</b> (cf. <figref idref="DRAWINGS">FIGS. 2, 3, 8 and 9</figref>). To do so, the user may grip dose knob <b>41</b> and pull it in the proximal direction. Dose member <b>34</b> moves proximally also with respect to the rotation member <b>21</b>. Proximal movement of the rotation member is prevented by support member <b>32</b> which abuts protruding member <b>33</b> of rotation member <b>21</b>. Consequently, the proximal movement of dose member <b>34</b> with respect to the housing part <b>17</b> is converted into rotational movement of the rotation member <b>21</b> in the first direction (arrow <b>44</b>) with respect to the housing part <b>17</b>, in particular on account of the threaded engagement of dose member <b>34</b> and rotation member <b>21</b>. Thus, the rotation member <b>21</b> rotates in the first direction—counter-clockwise as seen from the proximal end of the rotation member—with respect to the housing. Rotation member <b>21</b> also rotates with respect to the drive member <b>20</b> and to the stop member <b>26</b>. The drive member <b>20</b> is prevented from rotating in the first direction by interaction with the stop member <b>26</b>, e.g. by interlocking of toothings <b>27</b> and <b>28</b>. As the piston rod <b>12</b> is coupled to the drive member <b>20</b> and rotation in the first direction of the drive member would cause the piston rod to travel in the proximal direction, the piston rod <b>12</b> is prevented from being driven in the proximal direction by interaction of stop member <b>26</b> and drive member <b>20</b>. Dose accuracy can be increased in this way.

When the rotation member <b>21</b> rotates in the first direction, the ramps of the teeth of toothing <b>23</b> of rotation member <b>21</b> slide along the ramps of the teeth of toothing <b>22</b>. Thus, a tooth of the rotation member may index around the rotation axis until the tooth engages one of the next teeth of toothing <b>22</b> of drive member <b>20</b>. The teeth of rotation member <b>21</b> slide along the ramps of the teeth of drive member <b>20</b>. During this movement, drive member <b>20</b> and, in particular, stop member <b>26</b> are displaced along the rotation axis with respect to piston rod <b>12</b> and housing by a distance determined by, preferably equal to, the depth of a tooth of toothing <b>22</b>, before a tooth of toothing <b>23</b> (totally) disengages that tooth of toothing <b>22</b>. Afterwards, the tooth of the rotation member <b>21</b> engages the next tooth of toothing <b>22</b> and the force provided by resilient member <b>31</b> moves drive member <b>20</b> and, in particular, stop member <b>26</b> back along the rotation axis into the axial start position. An according movement of stop member and drive member in the distal direction and back into the proximal direction is indicated by double arrow <b>45</b> in <figref idref="DRAWINGS">FIGS. 2 and 3</figref>.

A tooth of the rotation member which engages the next tooth of the drive member may cause an audible and/or tactile feedback to the user.

The drive mechanism is suitable for a fixed dose device or a user settable dose device. The size of the fixed dose of medication which is to delivered or the increments in which a user-settable dose may be varied by a user are preferably determined by the distribution of the teeth of the respective toothings in the drive member, rotation member and stop member. The rotation member may be rotated over more than one teeth (dose increment) of the drive member for a user-settable dose device and over one teeth (only) for a fixed dose device. The number of teeth in the drive member <b>20</b> over which the rotation member <b>21</b> rotates during dose setting determines the size of the dose which is actually delivered. The dose member and the rotation member may be adapted to one another such that the rotation member may rotate only by one tooth for a fixed dose device and by more than one tooth for a variable dose device.

After the dose has been set, the dose part <b>16</b> and with it the dose member <b>34</b> is moved (pushed) by the user in the distal direction with respect to housing part <b>17</b> (arrow <b>46</b>; cf. <figref idref="DRAWINGS">FIGS. 4, 5, 8 and 9</figref>). Thus, the dose member <b>34</b> is moved in the distal direction with respect to the housing part <b>17</b>. The rotation member <b>21</b> accordingly rotates in the second direction, which is opposite to the first direction, with respect to the housing (arrow <b>47</b>, cf. <figref idref="DRAWINGS">FIGS. 4 to 9</figref>). Drive member <b>20</b> follows rotational movement of the rotation member in the second direction. Rotational movement of the drive member <b>20</b> in the second direction is converted into rotational movement of the piston rod <b>12</b> in the second direction, which movement, in turn, is converted into movement of the piston rod <b>12</b> in the distal direction. Accordingly, the piston <b>10</b> of <figref idref="DRAWINGS">FIG. 1</figref> may be displaced in the distal direction with respect to the cartridge <b>4</b> and a dose of medication <b>5</b> is dispensed from the cartridge the amount of which corresponds to the previously set dose.

During dose delivery, toothings <b>22</b> and <b>23</b> interlock and ramps of the teeth of toothing <b>28</b> of the drive member <b>20</b> slide along ramps of the teeth of toothing <b>27</b> of stop member <b>26</b>. This movement is similarly as described above for the relative rotational movement of rotation member and drive member with opposite rotation direction. The stop member <b>26</b> is thereby displaced in the distal direction with respect to the drive member <b>20</b> by a distance corresponding to the depth of a tooth of toothing <b>27</b> in stop member <b>26</b>. Resilient member <b>28</b> forces the stop member <b>26</b> back into the axial starting position, when the next tooth of toothing <b>28</b> is engaged by the respective tooth of toothing <b>27</b> (double arrow <b>65</b>).

A tooth of the drive member which engages the next tooth of the stop member may cause an audible and/or tactile feedback to the user.

<figref idref="DRAWINGS">FIG. 10</figref> schematically shows an oblique sectional view of a second embodiment of a drive mechanism. This drive mechanism essentially corresponds to the one described in conjunction with <figref idref="DRAWINGS">FIGS. 2 to 9</figref>. In contrast thereto, the stop member <b>26</b> is secured against rotational movement and displacement with respect to the housing (<b>13</b>, <b>17</b>, <b>40</b>). Stop member <b>26</b> may be integrated in housing part <b>40</b> or <b>17</b> or an insert thereof. Housing part <b>40</b> may be housing <b>13</b>, for example. Housing part <b>17</b> may be inserted and fixed within housing <b>13</b>. Fixing elements <b>64</b> may engage corresponding elements in the housing for fixing the housing part <b>17</b> to housing part <b>40</b>.

In order to compensate for the relative axial displacement between rotation member <b>21</b>, drive member <b>20</b> and stop member <b>26</b>, when the respective parts rotate with respect to one another, the rotation member <b>21</b> is movable with respect to the housing. In order to keep stop member <b>26</b> and rotation member <b>21</b> in, preferably permanent, abutment with drive member <b>20</b> during medication delivery operation of the drive mechanism, resilient member <b>31</b> exerts a force on the rotation member <b>21</b>, preferably on protruding member <b>33</b> thereof which presses rotation member and drive member <b>20</b> towards stop member <b>26</b>. Resilient member <b>31</b> may be arranged at that side of the drive member which faces away from the stop member, e.g. its proximal side. Resilient member may abut the proximal face of protruding member <b>33</b>. Support member <b>32</b> can thus be dispensed with. The distal end face of housing part <b>17</b> may act as an abutment surface for the resilient member <b>31</b>.

However, when the elements are arranged as shown in <figref idref="DRAWINGS">FIG. 10</figref>, axial movement of the rotation member, which may occur correspondingly to the axial movement of the stop member in the previous embodiment, may be transferred to the dose part <b>16</b> and thereby to the user. This movement of an external part might be irritating for a user.

<figref idref="DRAWINGS">FIGS. 11 to 15</figref> schematically show a third embodiment of a drive mechanism which is suitable for being provided in the medication delivery device <b>1</b> as described in conjunction with <figref idref="DRAWINGS">FIG. 1</figref>.

The drive mechanism essentially corresponds to the one described in connection with the previous embodiments. In contrast thereto, the drive member <b>20</b> and, in particular, the rotation member <b>21</b> are rotatable around a rotation axis which runs obliquely with respect to the axis along which the piston rod <b>12</b> is displaced (displacement axis). The rotation axis (cf. axis A in <figref idref="DRAWINGS">FIG. 14</figref>) may run transversally, in particular perpendicularly, with respect to the displacement axis and, in particular, with respect to a main direction of extent of the piston rod <b>12</b>.

Drive member <b>20</b> and rotation member <b>21</b> may be retained by an axis member <b>50</b>, which may extend through rotation member <b>21</b> and drive member <b>20</b>. Axis A may run along axis member <b>50</b>. Axis member may secure drive member and rotation member against displacement with respect to the housing. Stop member <b>26</b> may be integrated into housing <b>13</b>. Of course, stop member <b>26</b> may also be embodied as a separate element. Axis member <b>50</b> may extend through stop member <b>26</b>.

Drive member <b>20</b> comprises an outer toothing <b>51</b>. Teeth of the outer toothing <b>51</b> may extend radially away from rotation axis A. Drive member may be a toothed gear sleeve. The piston rod <b>12</b> is expediently provided with an outer toothing <b>52</b>. The outer toothing <b>52</b> of piston rod <b>12</b> and the outer toothing <b>51</b> of the drive member <b>20</b> are arranged to engage one another. The outer toothing <b>52</b> of piston rod <b>12</b> and the outer toothing <b>51</b> of the drive member <b>20</b> may be permanently engaged. When the drive member <b>20</b> and the rotation member <b>21</b> rotate together in the second direction with respect to the housing <b>113</b>, the piston rod <b>12</b> is also displaced in the distal direction with respect to the housing. The piston rod does not rotate while it is displaced in the distal direction with respect to the housing.

The piston rod <b>12</b> may be supported against deviation in the radial direction with respect to the displacement axis, fir example by means of housing part <b>17</b> through an opening <b>53</b> in which the piston rod may extend.

In contrast to the previously described embodiments, the dose member <b>34</b> and the rotation member <b>21</b> are not threadedly engaged. Rather, rotation member <b>21</b> and dose member <b>34</b> are connected/coupled to one another via a lever mechanism. The lever mechanism is adapted to convert movement of the dose member <b>34</b> with respect to the housing in the proximal direction into rotational movement of the rotation member in the first direction with respect to the housing and movement of the dose member <b>34</b> with respect to the housing in the distal direction into rotational movement of the rotation member in the second direction with respect to the housing.

Drive member <b>20</b> is prevented to rotate during setting of the dose on account of the stop member <b>26</b> preventing rotational movement of the drive member in the first direction.

The lever mechanism may comprise a lever <b>55</b>. Lever <b>55</b> is preferably secured against rotational movement with respect to rotation member <b>21</b> and preferably against (simultaneous) translational movement with respect to rotation member <b>21</b>. Preferably, lever <b>55</b> is formed unitary with rotation member <b>21</b>. Lever <b>55</b> is pivotally around the rotation axis in the first direction during dose setting and in the second direction during dose delivery.

Dose member <b>34</b> may, preferably at its distal end, comprise an engagement member <b>54</b>, e.g. a pin, for engagement with the lever <b>55</b>. Engagement member <b>54</b> may engage the lever <b>55</b>, in particular an opening <b>56</b>, preferably an elongate opening <b>56</b> within lever <b>55</b>.

Stop member <b>26</b> prevents rotational movement of the drive member in the first direction during dose setting as described previously.

<figref idref="DRAWINGS">FIG. 16</figref> shows a schematic sectional view of a part of a resettable drive mechanism according to an embodiment in a delivery state. <figref idref="DRAWINGS">FIG. 17</figref> shows the resettable drive mechanism of <figref idref="DRAWINGS">FIG. 16</figref> in a reset state.

The drive mechanism may correspond to the one described in conjunction with <figref idref="DRAWINGS">FIGS. 2 to 9</figref>. However, a reset mechanism for a drive mechanism as it is described in more detail below may also be provided for in the remaining drive mechanisms as described above.

The drive mechanism described in conjunction with <figref idref="DRAWINGS">FIGS. 15 and 16</figref> is a resettable drive mechanism. For this purpose, the drive mechanism comprises a reset mechanism. The reset mechanism may be switched between a reset position and a delivery position.

In contrast to the drive mechanism described in conjunction with the previous figures, the rotation member <b>21</b> is not shown in <figref idref="DRAWINGS">FIGS. 16 and 17</figref>. However, a rotation member may nevertheless be provided. <figref idref="DRAWINGS">FIGS. 16 and 17</figref> only show a half of a section through the drive mechanism. The additional cut was made along piston rod <b>12</b>.

As shown in <figref idref="DRAWINGS">FIG. 16</figref>, in the delivery state, drive member <b>20</b> and stop member <b>26</b> are engaged with one another such that rotational movement of the drive member <b>20</b> with respect to housing <b>13</b> in the first direction is prevented and rotation of the drive member <b>20</b> in the second direction, opposite to the first direction, is allowed. Toothings <b>27</b> and <b>28</b> may be provided for this purpose as described further above. Resilient member <b>31</b> exerts a force acting in axial direction on stop member <b>26</b>, said force tending to keep the stop member and the drive member engaged. Resilient member <b>31</b> may be arranged to keep stop member in engagement and, in particular, in abutment with drive member <b>20</b> in the delivery state. The (biased) resilient member <b>31</b> may be supported by and, preferably, bear against bearing member <b>57</b>. Bearing member may be support <b>48</b> of <figref idref="DRAWINGS">FIG. 6</figref>, for example. Bearing member <b>57</b> is expediently secured against rotational movement and displacement with respect to housing <b>13</b>.

Rotation of the drive member <b>20</b> in the second direction may cause the piston rod <b>12</b> to be displaced in the distal direction with respect to housing <b>13</b>. The piston rod <b>13</b> may rotate and translate in the distal direction with respect to the housing for dose delivery as described in conjunction with <figref idref="DRAWINGS">FIGS. 2 to 10</figref>. Alternatively, the piston rod may be moved in the distal direction with pure translatory movement (not explicitly shown, cf. a drive mechanism according to <figref idref="DRAWINGS">FIGS. 11 to 15</figref>). The drive member <b>20</b> may engage the piston rod <b>12</b>. The drive member <b>20</b> may be splined to the piston rod <b>12</b>. Preferably, there is no relative rotational movement possible between piston rod <b>12</b> and drive member <b>20</b>. Also, the drive member <b>20</b> preferably cannot be rotated in the first direction on account of the (permanent) interlocking of the drive member <b>20</b> and the stop member <b>26</b> when the reset mechanism is in the delivery state.

Thus, when the drive mechanism is in the delivery state, movement of the piston rod <b>12</b> in the proximal direction with respect to housing <b>13</b> to a starting position is prevented, because the stop member <b>26</b> prevents rotation of the drive member <b>20</b> in the first direction and the drive member has to be rotated in the first direction, if the piston rod <b>12</b> was to be moved in the proximal direction with respect to the housing <b>13</b> into the starting position.

However, after a cartridge <b>4</b> has been emptied, i.e. after a distal end position of the piston <b>10</b> and, in particular, of the piston rod <b>12</b> has been reached, the piston rod has to be moved in the proximal direction back into a proximal starting position in order to allow the drive mechanism to be reused. Expediently, the drive mechanism is configured to be switchable from the delivery state to a reset state. In the reset state, the piston rod <b>12</b> may be moved in the proximal direction with respect to the housing, for example by a user screwing and/or pushing the piston rod <b>12</b> in the proximal direction.

The drive mechanism comprises a clutch member <b>58</b>. Clutch member <b>58</b> is movable with respect to housing <b>13</b>, preferably displaceable with respect to the housing, between a delivery position D and a reset position R. The clutch member <b>58</b> may be moved back and forth between the delivery position and the reset position. The reset position may be arranged in the distal direction as seen from the delivery position.

The clutch member <b>58</b> may be a sleeve. Piston rod <b>12</b> may extend through clutch member.

In the delivery position, drive member <b>20</b> and stop member <b>26</b> are engaged, in the reset position, drive member <b>20</b> and stop member <b>26</b> are disengaged (cf. the encircled region <b>59</b> in <figref idref="DRAWINGS">FIG. 17</figref>). Thus, when the clutch member <b>58</b> is in the reset position, the drive member may be rotated in the first direction with respect to the housing <b>13</b> without the stop member <b>26</b> preventing the rotation. Consequently, the piston rod <b>12</b> may be moved in the proximal direction, e.g. by rotation with respect to the housing and on account of a threaded engagement to the housing, due to the drive member <b>20</b> and the stop member <b>26</b> being disengaged.

The clutch member <b>58</b> may comprise a protrusion <b>61</b>. Protrusion <b>61</b> may protrude radially and preferably inwardly from a base portion <b>66</b> of the clutch member <b>58</b>. The base portion may extend in the axial direction. Protrusion <b>61</b> may be arranged to move the drive member <b>20</b> and the stop member <b>26</b> out of engagement when the clutch member is moved towards reset position R. Protrusion <b>61</b> may be provided at or near the proximal end of the clutch member <b>58</b>. A distal end face of protrusion <b>61</b> of clutch member <b>58</b> may be arranged to couple to and preferably to abut a proximal face of stop member <b>26</b>.

The reset mechanism furthermore comprises a clutch resilient member <b>60</b>, for example a clutch spring member, like a coil spring and/or a compression spring, for example.

The clutch member <b>58</b> may extend along drive member <b>20</b>, stop member <b>26</b>, resilient member <b>31</b>, bearing member <b>57</b> and/or clutch resilient member <b>60</b>. The clutch member <b>58</b> may be rigid. The clutch member <b>58</b> may have a constant length.

Clutch resilient member <b>60</b> may be biased when the clutch member <b>58</b> is in the delivery position. Biased clutch resilient member may exert a force on the clutch member that tends to move the clutch member in the reset position. Clutch resilient member <b>60</b> may bear on bearing member <b>57</b>, in particular on a distal face thereof.

Clutch member <b>58</b> may comprise a (additional) protrusion <b>62</b>. Protrusion <b>62</b> may protrude radially and preferably inwardly from the base portion <b>66</b> of the clutch member <b>58</b>. Protrusion <b>62</b> may be arranged in the region of the distal end of the clutch member <b>58</b>. Protrusion. <b>62</b> may be arranged to be abuttable by and is preferably abutted by clutch resilient member <b>60</b>. Clutch resilient member <b>60</b> may be supported by and, in particular, bear on a proximal face of protrusion <b>62</b>.

The clutch resilient member <b>60</b> is arranged to exert a force on the clutch member <b>58</b> which force tends to move the clutch member <b>58</b> in the reset position R. When the drive mechanism is in the delivery state, this force is counteracted by a clutch stop member <b>63</b>. Accordingly, in the delivery state, clutch member <b>58</b> may be held in the delivery position by the clutch stop member <b>63</b>.

In the delivery state, clutch stop member <b>63</b> is preferably secured against displacement with respect to the housing <b>13</b>. Clutch stop member <b>63</b> may be arranged to abut clutch member <b>58</b>. A proximal end face of the clutch stop member <b>63</b> may abut a distal end face of the clutch member <b>58</b> in the delivery state.

For resetting the device, the clutch stop member <b>63</b> may be moved, for example removed, so as to allow the clutch member to move into the reset position. Thereupon, biased clutch resilient member <b>60</b> which exerts the force, which is no longer compensated by clutch stop member, on clutch member <b>58</b>. The force automatically tends to move clutch member <b>58</b> in the reset position R. The clutch member <b>58</b> may abut stop member <b>26</b>. Stop member <b>26</b> may tend to follow movement of the clutch member towards the reset position R.

In order to get into reset position the force exerted by the resilient member <b>31</b> on the stop member <b>26</b>, which force tends to hold drive member <b>20</b> and stop member <b>26</b> in engagement, has to be overcome. Thus, the force moving the clutch member <b>58</b> towards the reset position <b>58</b> has to be greater than the force exerted by the resilient member <b>31</b>. The force for moving and, in particular, holding the clutch member <b>58</b> in reset position R may be provided for by clutch resilient member <b>60</b>. It is expedient for the resilient member <b>31</b> and the clutch resilient member <b>60</b> to be embodied as a spring member, respectively. Clutch resilient member <b>60</b>, in this case, preferably has a spring strength greater than the one of resilient member <b>31</b> in order to overcome the force exerted by resilient member <b>31</b>.

The clutch stop member <b>63</b> is expediently formed in the cartridge unit, for example, by the cartridge <b>4</b> or the cartridge retaining member <b>11</b>. Thus, if the cartridge unit is detached from the housing <b>13</b> for replacing an empty cartridge, the clutch member <b>58</b> is moved, preferably automatically, towards and into the reset position and preferably held in the reset position.

The distance by which the clutch member <b>58</b> moves with respect to the housing <b>13</b> when moving from delivery position into reset position is preferably chosen to be great enough to disengage toothings <b>27</b> and <b>28</b>.

The clutch member <b>58</b> is expediently secured to the drive mechanism in order to avoid the clutch member falling out of the housing. For this purpose, the clutch member may abut a proximal face of the stop member <b>26</b>.

As shown in <figref idref="DRAWINGS">FIG. 17</figref>, when the clutch member <b>58</b> is in reset position R, the drive mechanism is in the reset state and the piston rod <b>12</b> may be moved in the proximal direction with respect to the housing from a distal end position back into a proximal starting position. When a new cartridge <b>4</b> is attached to the housing <b>13</b>, after the piston rod <b>12</b> was moved back into starting position, clutch member <b>58</b> may be moved into the distal direction back into delivery position together with the cartridge <b>4</b> and, if present, the cartridge retaining member <b>11</b>, thereby moving drive member <b>20</b> and stop member <b>26</b> again into engagement.

Accordingly, the medication delivery device may be reused. As an element of the cartridge unit like cartridge <b>4</b> or cartridge retaining member <b>11</b> may serve as the clutch stop member <b>63</b>, the reset mechanism may automatically and, in particular (purely) mechanically, decouple stop member <b>26</b> and drive member <b>20</b>, when the cartridge unit <b>2</b> is detached from the drive unit <b>3</b> (cf. <figref idref="DRAWINGS">FIG. 1</figref>). Thus, the only action required by a user is to move, e.g. screw and/or push, the piston rod <b>12</b> back into the starting position before a new cartridge unit <b>2</b> may be attached to the drive unit <b>3</b>. The drive mechanism is thus easily reusable.

The reset mechanism described herein above may be implemented easily and requires only a small amount of additional parts such as compared to the corresponding non-resettable drive mechanism. In particular, such as compared to the first embodiment, only two additional parts—clutch member and clutch resilient member—are required for the automatic reset mechanism.

As the reset mechanism may be an automatic one, no external action is required for disengaging stop member and drive member. Thus, the clutch member may be retained in the housing and, in particular, inaccessible from the outside.

Of course, the reset mechanism may be implemented as a manual, non-automatic mechanism. It is expedient, in this case, to configure the movement of the clutch member to be externally actuable.

In contrast to the situation depicted in <figref idref="DRAWINGS">FIGS. 16 and 17</figref>, the clutch member <b>58</b> may be (partly) arranged outside of the housing. The housing may be provided with one or more openings through which the clutch member may extend from the outside to the inside of the housing. This is particularly expedient for a non-automatic reset mechanism.

With the (resettable) drive mechanisms described herein above a good dose accuracy may be achieved. The drive mechanisms are particularly suitable for dispensing doses of the medication from and including 1 IU up to and including 30 IU, (preferably from and including 3 IU up to and including 20 IU. Also, doses of 30 IU or more or 1 IU or less may be dispensed by means of the described drive mechanisms. However, doses of from and including 1 IU up to and including 30 IU are particularly suitable. For example, if a device described in conjunction with <figref idref="DRAWINGS">FIGS. 1 to 10</figref>, in which the piston rod rotates during displacement, was to be designed for doses less than 1 IU, the thread of the piston rod should have a low pitch and/or the number of teeth of the respective toothing of drive member and rotation member should be increased. Of course, the production costs may increase on account of the finer segmentation of the toothings and the lower pitch thread. In order to provide for a device configured to deliver doses greater than 30 IU, e.g. 50 IU or greater, the thread in the piston rod should have a higher pitch. Consequently, small deviations from a predetermined course of the thread result in major absolute deviations from the desired dose. Thus, the risk of a reduction in dose accuracy may be increased. In addition, the risk of self-locking of a threaded engagement may be increased.

A diameter of the (outer) housing of the medication delivery device may be less than or equal to 20 mm, preferably less than or equal to 16 mm, particularly preferably less than or equal to 14 mm.

A first aspect of the invention provides a drive mechanism for a medication delivery device (<b>1</b>), comprising: <ul id="ul0001" list-style="none"><li id="ul0001-0001" num="0000"><ul id="ul0002" list-style="none"><li id="ul0002-0001" num="0153">a housing (<b>13</b>, <b>17</b>, <b>40</b>) having a proximal end and a distal end,</li><li id="ul0002-0002" num="0154">a rotation member (<b>21</b>) which is adapted to be rotated in a first direction with respect to the housing during setting of a dose of a medication (<b>5</b>) and to be rotated in a second direction with respect to the housing during delivery of the dose, the second direction being opposite to the first direction,</li><li id="ul0002-0003" num="0155">a piston rod (<b>12</b>) which is adapted to be displaced in a distal direction with respect to the housing for delivering the dose,</li><li id="ul0002-0004" num="0156">a drive member (<b>20</b>) which follows rotational movement of the rotation member in the second direction during delivery of the dose, and</li><li id="ul0002-0005" num="0157">a stop member (<b>26</b>) which prevents rotational movement of the drive member with respect to the housing in the first direction during setting of the dose, wherein the rotational movement of the drive member in the second direction is converted into movement of the piston rod in the distal direction with respect to the housing.</li></ul></li></ul>

A second aspect provides a drive mechanism according to the first aspect, wherein the drive mechanism comprises a dose member (<b>16</b>, <b>34</b>, <b>41</b>) which is moveable with respect to the housing (<b>13</b>, <b>17</b>, <b>40</b>) during setting and delivery of the dose, and wherein movement of the dose member with respect to the housing is converted into rotational movement of the rotation member with respect to the housing.

A third aspect provides a drive mechanism according to the second aspect, wherein the dose member (<b>16</b>, <b>34</b>, <b>41</b>) is secured against rotational movement with respect to the housing (<b>13</b>, <b>17</b>, <b>40</b>).

A fourth aspect provides a drive mechanism according to any one of the first through third aspects, wherein the drive member (<b>20</b>) and the rotation member (<b>21</b>) are rotatable about a common rotation axis.

A fifth aspect provides a drive mechanism according to the fourth aspect, wherein the piston rod (<b>12</b>) is displaced in the distal direction with respect to the housing (<b>13</b>, <b>17</b>, <b>40</b>) along the rotation axis.

A sixth aspect provides a drive mechanism according to the fourth aspect, wherein the piston rod (<b>12</b>) is displaced in the distal direction with respect to the housing (<b>13</b>, <b>17</b>, <b>40</b>) transversally with respect to the rotation axis.

A seventh aspect provides a drive mechanism according to any one of the second through sixth aspects, wherein the dose member (<b>16</b>, <b>34</b>, <b>41</b>) and the rotation member (<b>21</b>) are threadedly engaged.

An eighth aspect provides a drive mechanism according to any of the second through sixth aspects, wherein the dose member (<b>16</b>, <b>34</b>, <b>41</b>) and the rotation member (<b>21</b>) are coupled to one another by a lever (<b>55</b>), the lever being pivotally around the rotation axis during movement of the dose member for setting and delivery of the dose.

A ninth aspect provides a drive mechanism according to any one of the first through eighth aspects, wherein the drive member (<b>20</b>) abuts stop member (<b>26</b>) and rotation member (<b>21</b>) during movement of the rotation member for setting and delivery of the dose.

A tenth aspect provides a drive mechanism according to any one of the first through ninth aspects, wherein the rotation member (<b>21</b>) and the stop member (<b>26</b>) are held in abutment with the drive member (<b>20</b>) by a force provided by a spring member (<b>31</b>) during setting and delivery of the dose.

An eleventh aspect provides a drive mechanism according to any one of the first through tenth aspects, wherein the drive member (<b>20</b>) and the rotation member (<b>21</b>) are coupled to one another by a first uni-directional friction clutch mechanism, which is configured to permit relative rotational movement between rotation member and drive member during rotation of the rotation member in the first direction for setting of the dose and to prevent relative rotational movement of rotation member and drive member during rotation of the rotation member in the second direction for delivery of the dose.

A twelfth aspect provides a drive mechanism according to any one of the first through eleventh aspects, wherein the drive member (<b>20</b>) and the stop member (<b>26</b>) are coupled to one another by a second unidirectional friction clutch mechanism, which is configured to prevent relative rotational movement between stop member and drive member during rotation of the rotation member (<b>21</b>) in the first direction for setting of the dose and to permit relative rotational movement of stop member and drive member during rotation of the rotation member in the second direction for delivery of the dose.

A thirteenth aspect provides a drive mechanism according to any one of the first through twelfth aspects, wherein the stop member (<b>26</b>) is secured against rotational movement with respect to the housing (<b>13</b>, <b>17</b>, <b>40</b>).

A fourteenth aspect provides a drive mechanism according to any one of the first through thirteenth aspects, wherein the stop member (<b>26</b>) is moveable in an axial direction with respect to the housing (<b>13</b>, <b>17</b>, <b>40</b>).

A fifteenth aspect provides a medication delivery device (<b>1</b>) comprising the drive mechanism according to any one of the first through fourteenth aspects, and a cartridge (<b>4</b>), the cartridge holding a plurality of doses of the medication (<b>5</b>).

Of course, the invention is not restricted by the embodiments described above.